A woman has gone on trial accused of being a "trusted" member of an extremist animal rights group that carried out a blackmail campaign against a major animal-testing company.

Debbie Vincent, 52, along with members of the Stop Huntingdon Animal Cruelty (Shac) group, is accused of conspiring to blackmail the Cambridge-based Huntingdon Life Sciences (HLS) over a 10-year period.

Michael Bowes QC, prosecuting, said protests targeting suppliers and customers of HLS had included false accusations of paedophilia against staff, sending incendiary devices and hoax bombs, posting sanitary towels claimed to be infected with Aids, and causing criminal damage to people's homes and cars.

Bowes told Winchester crown court that the aim of the campaign had been to put HLS out of business by cutting off its suppliers in a climate of fear.

The main tactic had been to publish the names of companies linked to HLS, and even of those linked solely to its suppliers, on the Shac website, jurors heard. Publication would lay the firms open to illegal acts of intimidation and violence,

Bowes said: "The threat was chillingly basic: companies were told, [you are] on the website until you publish your surrender, and once you do we will very kindly take you off."

He said Vincent had worked with the pair behind Shac, Greg and Natasha Avery, at their headquarters, in Little Moorcote, near Hook, Hampshire. She had even been given access to the computer used to co-ordinate the illegal actions, he said.

The pair were among seven defendants jailed for a total of 50 years in 2009 for their part in the conspiracy.

Bowes said surveillance had been carried out on the Shac headquarters as part of the police investigation, which recorded telephone conversations showing Vincent's involvement in the organisation of the group's activities.

He said: "It's quite obvious that Debbie Vincent was trusted: she was an insider, allowed to go on the computer, and undoubtedly knew what was going on."

Bowes said Vincent's role with Shac, from November 2001 to August 2011, had become more substantial after the jailing of the Averys and other members of the group in January 2009.

The jury was shown an interview Vincent gave to the BBC during the month after the arrests.

She said during the interview: "People are frustrated over the inaction of the government and the vested interest from the vivisection industry in addressing these important issues.

"And there will be more direct – what people call clandestine – action."

Bowes said: "Given the scale of this operation, she must have known, and indeed did know, what was going on."

The actions of Shac had gone beyond the right to protest, or freedom of expression, he said.

He said: "People are entitled to hold strong views in this country, and freedom of expression is one of our most cherished liberties. But what people are not entitled to do is menace others with their demands, and this is about the making of unwarranted demands with menaces."

Bowes said the Shac website, where suppliers' names were published, had been used as a "veneer of respectability", while a second website, called Biteback, was used to list the illegal actions that had been carried out.

Bowes said the previous trial of other Shac members had shown direct links between the two websites.

He said: "The campaign was thought to be very successful because it seemed to be working, as all they had to do was make these threats … such was the climate of fear that was engendered because it was always backed up by the nasty stuff, which they pretended wasn't them.

"It got to the position where a mere threat that you would go on the website would be so strong that the company would indeed surrender."

Vincent, of Pampisford Road, Croydon, south London, denies the charge of conspiracy to commit blackmail.

She was arrested in July 2012 at the same time as the Swiss-born Sven van Hasselt and a British woman, Natasha Simpkins, who was born in Germany. They were detained in the Netherlands and are still awaiting extradition to the UK to face the same charge. The trial continues.